High temperature thermostatic metal



Jan. 15, 1935. H. SCOTT 1,987,714

HIGH TEMPERATURE THERMOSTATIC METAL Filed Sept. 22, 1931 ITN ss s:INVENTOR I -Hovmrd Scuff 1/ v ATTORNEY Patented Jan. 15, 1935 I I a i IUNITED STATES PATENT OFFICE 4 1,987,714 HIGH TEMPERATURE THERMOSTATICMETAL Howard Scott, Wllkinsburg, Pa., assignor to Westinghouse Electric8; Manufacturing Company, a corporation of Pennsylvania ApplicationSeptember 22, 1931,8erlal No. 564,268 2 Claims. (01'. 291-15) Myinvention relates to thermally actuable deof a bimetal element of thesealloys is relatively vices and particularly to bimetal thermostatic hardto accomplish and is, therefore, somewhat members. expensive. 1

Among the objects of my invention are the 101- Further experimental workalong this line has lowing: To provide a bimetal combination of twoindicated that the lack of ductility and the ex- 5 alloys of diflerenttemperature expansivities that cessive hardness of the alloy includingup to shall have of the same order'of hardness; to pro- 25% of manganesecan be overcome bythe use vide a high expansion component in a bimetalof relatively larger manganese contents, and I element that shall beductile and that shall not have found it possible to use up tosubstantially 10 have excessive hardness; to provide a bimetal 36%manganese, which is a greater percentage 10 combination that shall havesuchcharacteristics than would theoretically have seemed desirable. asto the relative hardness of the two compo- One of the resultsaccompanying the use of nents as will permit of fabricating the samerela higher percentage of manganese is that the atively easily; toprovide a bimetal element that temperature a which its n ivity chanshall have a relatively large coefllcient of deflecr p y from a W V l toa hi h V l i m- 15 tion with apredetermined change of temperature.creased. The t mp ratur fli nt 0 pa In practicing my invention I providea bimetal sion is, ho not Changed pp y from element made up of twoiron-base alloys, the high that of the alloy containing not over 25% ofexpansion component being a manganese-iron manganese above about 200 C.

alloy having over 23% of manganese, while the It a higher deflection isdesired at the lower 20 low expansion component is a nickel-iron alloy tmp atur s, I may Obtain the a y d n with which may be mixed anappreciable per- 8n alloyi g eleme t 01 t e Order Of 185$, centage ofcobalt. The two components of such either singly or in combination, ofnickel, copper,

a bimetal element may be operatively associated cobalt, chr mium.Silicon, molybdenum, 0 t

25 with each other in any desired manner usually sten, to the iron-basealloy containing 23% to 25 practiced in this art. 36% of manganesawithout serious loss in due- Thesingle figure of the drawing illustratesa tility. It may be desirable to maintain the combimetal strip or barembodying my invention and bined percentage of manganese and one or acomshown in section. bination of the above-enumerated metals so as In myPatent No. 1,671,491, I have disclosed and not to materially exceed thati n 30 claimed a high-expansion component for a bistantially 5% of oneor of a combination of the. metal element that includes specifically analloy above-enumerated seven metals is used, the perof iron embodyingnot over 30% of manganese, centage content of manganese should notexceed which is operatively associated with a nickel-iron 31% or 32%.This composition is set vforth in 35 alloy containing up to orapproximately 45% combinationVI of TableIwhere the five percent 35nickel. I have found that a bimetal element of of added elements is tobe considered as including the kind disclosed and claimed in this patenthas a group consisting of these metals used singly or desirableproperties for use at temperatures havin combination. ing an averagevalue of about 300 C. I have The single figure of the drawingillustrates a also found, however, that a bimetal combination strip orbar of bimetal in which the high-expan- '40 of thiskind, andparticularly the high-expansion sion component 11 is a manganese-ironalloy component thereof, suffers from a lack of ductility embodying thecomposition hereinafter set forth and is excessively hard, so that thefabrication in Table I, while component 121s a nickel-cobalt- I TABLE I45 High. expansion component Manganese Carbon Silicon egg g PercentPercent Percent Patent 1 I 28to36 .05to.30 .05tol.0 0M2 Do. I1 30 to 33.05 to .30 .05 to 1.0 0 to 2 D0. III 30.5 .16 .17 0 to 1 Do. IV 28t036.05t0.30 ..05tol.0 0tol Do. V 26to36 .05to.30 .05tol.0 0to2 D0. VI 23 to31 .05 to .30 .05 to 1.0 l to 5 D0. 56

iron alloy which may be made up of any one of the combinationshereinbelow shown in Table 11.

hereinbefore stated, the coeillcient of deflection can be increasedsomewhat by the addition of an Tun: II I Low expansion component Addedele- Remainder Nickel Cobalt Manganese Silicon menu on Percent PercentPercent Percent Percent A 25to50 6 .06tol.0 .05to.6 Otol Do. B 29.8 16.5 .22 .05 to .5 to 1 Do. 0 26to32 3t020 .05tol .05to.5 0to2 Do. D 35to60.lto2 .05tol .05to.5 0M2 Do. E 45.2 .1 to 2 .06 to .53 .01 to .07 0 to 1Do.

. have found it possible also to use substantially 30.5% of manganese,.15% of carbon, .17% silicon, less than 1% of incidental constituentswith the remainder being iron and obtain substantially the same resultsas to ductility and hardness. By the incidental constituents, I mean theusual small quantities of impurities of one kind and another which areusually found to be present in an alloy or metal and which are of noparticular effect as regards the particular characteristics which it isdesired that the alloy or metal shall have.

Referring to the low expansion component set forth in Table II, it maybe noted that I prefer to use more than 25% of nickel and may even useup to 50% of nickel, in combination with cobalt varying from 3% to 20%,from .05 to 1% of manganese, from .0l% to 5% of silicon, from a trace to2% of incidental constituents, the remainder being iron or steel.

By virtue of the lower hardness and higher ductility of thehigher-manganese, iron-base alloys, as compared to such alloys havingabout 23% of manganese, bimetal elements made from the former, incombination with a low-expansion nickel-steel, may be fabricated, as bybeing welded or fused one to another, relatively easily, and may then bemuch more easily rolled, either cold or hot, (than bimetal elementsusing the 23 percent manganese steel) to the desired degree ofthickness. The bimetal element or slab thus acts, in general, as asingle metal element or slab, that is, the initial relative thicknessesof the two components will remain the same no matter how alloyingelement which may be either one or a combination of metals hereinbeforeenumerated, all of which have relatively high temperature expansivities,the amount or percentage of the alloying element being relatively smallbut very effective.

The difference in expansivities of the two components has been found tobe not more than l2.0 per C. at 100 C. and greater than 15.0 10- per C.at 300 C.

Various modifications may be made in my invention without departing fromthe spirit and scope thereof, and I desire, therefore, that only suchlimitations shall be placed thereon as are imposed by the prior art orare set forth in the appended claims.

I claim as my invention:

1. A bimetal element including two cooperating components havingdifferent temperature expansivities, the high expansion component beingan alloy including from twenty-six to thirty-six percent of manganese,between one tenth percent to one percent of incidental constituents,from one to five percent of any one of the following or any combinationthereof; copper, cobalt, chromium, nickel, silicon, molybdenum,tungsten, the remainder being principally iron, the low expansioncomponent being an alloy including between twenty-flve to fifty percentnickel, approximately fifteen percent cobalt, between one tenth percentand one percent incidental constituents', the remainder beingprincipally iron.

2. A bimetal element including two cooperating components havingdifierent temperature expansivities, the high expansion component beingan alloy including substantially thirty and one half percent ofmanganese, approximately fifteen hundredths percent of carbon,approximately seventeen hundredths percent of silicon, between one tenthand one percent of incidental constituents, between one and five percentof an alloying element from a group consisting of copper, cobalt,chromium, nickel, silicon, molybdenum, tungsten, the remainder beingmainly iron, the low-expansion component being an alloy includingtwenty-nine and eight tenths percent of nickel, approximately fifteenpercent of cobalt, approximately twenty-two hundredths percent ofmanganese, between one tenth and one percent of incidental constituents,the remainder being principally iron.

HOWARD SCOTT.

